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Home >> Toyota >> 2020 >> Corolla L >> Repair and Diagnosis >> External Pages >> Different car >> Section 324 (Meter / Gauge System (12.3 Inch) - Diagnostic Codes, Symptom Tests & Circuit Tests) >> METER / GAUGE SYSTEM (for 12.3 Inch Display) >> Speed Signal Circuit [11/2022 - ] >> Procedure

Speed Signal Circuit [11/2022 - ]: Procedure

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  1. INSPECT COMBINATION METER ASSEMBLY (INPUT WAVEFORM) 
    GTY1113432Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Component with harness connected
    (Combination Meter Assembly)
    *b Input Waveform
    1. Check the signal waveform according to the condition(s) in the table below.
      Item Condition
      Tester connection I4-25 (SI) - Body ground
      Tool setting 5 V/DIV., 20 ms./DIV.
      Condition Ignition switch ON, wheel being rotated
      NOTE:

      Perform the inspection from the back of the connector with the connector connected.

      HINT: 

      When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

      Result

      Result  Proceed to
      The measured waveform is similar to that in the illustration A
      The measured waveform is not similar to that in the illustration
      (Stuck low)      		 B
      The measured waveform is not similar to that in the illustration
      (Stuck high)      		 C

    Result: 

    B 

    See step  6

    Result: 

    C 

    See step  9

    Result: 

    A 

    See step  2

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM) 
    GTY1118307Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    *a Component with harness connected
    (Combination Meter Assembly)
    *b Output Waveform
    1. Check the signal waveform according to the condition(s) in the table below.
      Item Condition
      Tester connection I4-8 (+S) - Body ground
      Tool setting 5 V/DIV., 20 ms./DIV.
      Condition Ignition switch ON, wheel being rotated
      NOTE:

      Perform the inspection from the back of the connector with the connector connected.

      HINT: 

      • When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.
      • The waveform (B) changes depending on the connected ECUs.

      Result

      Result  Proceed to
      The measured waveform is similar to that in the illustration A
      The measured waveform is not similar to that in the illustration
      (Stuck low)      		 B
      The measured waveform is not similar to that in the illustration
      (Stuck high)      		 C

    Result: 

    B 

    See step  4

    Result: 

    C 

    REPLACE COMBINATION METER ASSEMBLY 

    Refer to REMOVAL [11/2022 - 09/2024] , or refer to REMOVAL [09/2024 - ]

    Result: 

    A 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY) 
    1. Disconnect the A139 ECM connector.
    2. Disconnect the I55 radio and display receiver assembly connector.
    3. Disconnect the I68 stereo component amplifier assembly* connector.
    4. Disconnect the I4 combination meter assembly connector.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A139-42 (SPD) - I4-8 (+S) Always Below 1 Ω
      I55-8 (SPD) - I4-8 (+S) Always Below 1 Ω
      I68-11 (SPD) - I4-8 (+S)* Always Below 1 Ω
      1. *: for JBL Model

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    CHECK THE VOLTAGE AT TERMINAL SPD OF EACH ECU 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  4. INSPECT EACH ECU (INTERNAL SHORT) 
    1. Disconnect one of the connectors below.
      NOTE:

      After disconnecting a connector, perform all steps with all other devices connected.

      Connector ECU
      A139 ECM
      I55 Radio and display receiver assembly
      I68* Stereo component amplifier assembly
      1. *: for JBL Model
    2. Measure the voltage according to the value(s) in the table below.
      GTY1110292Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Combination Meter Assembly)
      NOTE:
      • Make sure to perform this inspection with the wheels stopped.
      • Perform the inspection from the back of the connector with the connector connected.

      Standard Voltage

      Tester Connection Condition Specified Condition
      I4-8 (+S) - Body ground Ignition switch ON 4.5 to 14 V
    3. Repeat steps (a) and (b) for each connected ECU.

      HINT: 

      If the waveform changes to the waveform shown in the illustration after disconnecting a connector, an internal short in the disconnected ECU is suspected.

      Result

      Result  Proceed to
      After performing the inspection procedure for all connectors, the voltage did not change to the specified voltage A
      When disconnecting the connector of the ECM, the voltage changed to the specified voltage B
      When disconnecting the connector of the radio and display receiver assembly, the voltage changed to the specified voltage C
      When disconnecting the connector of the stereo component amplifier assembly, the voltage changed to the specified voltage
      (for JBL Model)      		 D

    Result: 

    B 

    REPLACE ECM 

    Refer to REMOVAL [11/2022 - 09/2024] , or refer to REMOVAL [09/2024 - ]

    Result: 

    C 

    REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY 

    Refer to REMOVAL [11/2022 - 09/2024] , or refer to REMOVAL [09/2024 - ]

    Result: 

    D 

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY 

    Refer to REMOVAL [11/2022 - ]

    Result: 

    A 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY) 
    1. Disconnect the A139 ECM connector.
    2. Disconnect the I55 radio and display receiver assembly connector.
    3. Disconnect the I68 stereo component amplifier assembly* connector.
    4. Disconnect the I4 combination meter assembly connector.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A139-42 (SPD), I55-8 (SPD), I68-11 (SPD)* - I4-8 (+S) Always Below 1 Ω
      A139-42 (SPD), I55-8 (SPD), I68-11 (SPD)* or I4-8 (+S) - Body ground Always 10 kΩ or higher
      1. *: for JBL Model

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE COMBINATION METER ASSEMBLY 

    Refer to REMOVAL [11/2022 - 09/2024] , or refer to REMOVAL [09/2024 - ]

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  6. CHECK FOR DTC (SMART KEY SYSTEM (FOR START FUNCTION)) 
    1. Check if smart key system (for start function) DTCs are output.

      Body Electrical > Power Source Control > Trouble Codes 

      Result

      Result Proceed to
      DTCs are not output A
      DTCs are output B

    Result: 

    B 

    GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START (FOR START FUNCTION) 

    Refer to DIAGNOSTIC TROUBLE CODE CHART [11/2022 - 03/2023] , or refer to DIAGNOSTIC TROUBLE CODE CHART [03/2023 - 09/2024] , or refer to DIAGNOSTIC TROUBLE CODE CHART [09/2024 - ]

    Result: 

    A 

    See step  7

  7. INSPECT COMBINATION METER ASSEMBLY 

    HINT: 

    This procedure is performed to check the diode inside the combination meter assembly.

    1. Remove the combination meter assembly.

      Refer to REMOVAL [11/2022 - 09/2024] , or refer to REMOVAL [09/2024 - ]

    2. Measure the internal resistance of the combination meter assembly.

      Standard Resistance

      Tester Connection Tester Connection Condition Measured Value
      I4-6 (IG+) - I4-25 (SI)
      • Positive (+) tester probe → I4-6 (IG+)
      • Negative (-) tester probe → I4-25 (SI)
      		 Always A
      I4-6 (IG+) - I4-25 (SI)
      • Positive (+) tester probe → I4-25 (SI)
      • Negative (-) tester probe → I4-6 (IG+)
      		 Always B

      OK

      There is a large difference between the measured value (A) and the measured value (B).

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE COMBINATION METER ASSEMBLY 

    Refer to REMOVAL [11/2022 - 09/2024] , or refer to REMOVAL [09/2024 - ]

    Result: 

    OK 

    See step  8

  8. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - COMBINATION METER ASSEMBLY) 
    1. Disconnect the I167 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the I4 combination meter assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      I167-28 (SPDO) or I4-25 (SI) - Body ground Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 

    Refer to REMOVAL [11/2022 - 09/2024] , or refer to REMOVAL [09/2024 - ]

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  9. CHECK FOR DTC (SMART KEY SYSTEM (FOR START FUNCTION)) 
    1. Check if smart key system (for start function) DTCs are output.

      Body Electrical > Power Source Control > Trouble Codes 

      Result

      Result Proceed to
      DTCs are not output A
      DTCs are output B

    Result: 

    B 

    GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START (FOR START FUNCTION) 

    Refer to DIAGNOSTIC TROUBLE CODE CHART [11/2022 - 03/2023] , or refer to DIAGNOSTIC TROUBLE CODE CHART [03/2023 - 09/2024] , or refer to DIAGNOSTIC TROUBLE CODE CHART [09/2024 - ]

    Result: 

    A 

    See step  10

  10. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - COMBINATION METER ASSEMBLY) 
    1. Disconnect the I167 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the I4 combination meter assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      I167-28 (SPDO) - I4-25 (SI) Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) 

    Refer to REMOVAL [11/2022 - 09/2024] , or refer to REMOVAL [09/2024 - ]

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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